As mentioned in an earlier post I'll try to do one small PCB project every week and then send for PCB's of it every Monday.

Next week I'll do a slightly more advanced project than a simple breakout. I had this idea of making a very complex outline on a PCB and see if Seeedstudio and their fab house would accept it. I'm following the series Supernatural where the protagonists often stay at old motels with a lot of 50-60-70'ies decorations and furniture in them, so I decided to to a wall clock with a retro-inspired design.

The clock will have twelve "arms" each with a RGB PLCC6 (5050) SMD led at the end where hours, minutes and seconds will be represented by a color each.

I'll keep all the parts except for the leds on the backside to give an empty front where I can put some retro-pattern on the silk layer to enhance the retro feeling of it.

This week I have to go up to a 10x10 cm PCB instead of the 5x5 that the PAW designs should use, but I think it will be worth it...

Yes, that's a nice idea... Have the leds on the back side of the pcb as well, and then have it mounted 1/2 inch above a white frame that reflects the light from the leds. That might actually look cooler.... and not so modern with visible leds.

Not sure yet. Probably a small cheapass 20-pin PIC like PIC16F1829, I don't need any usb or fancy stuff in it for this project. I could go with a atmega168 as well, but that would feel so "Arduino" :-)

Then I'll have 6 latches 75HC573 in SSOP so I can direct drive all leds, no multiplexing required.

Haven't decided on the clock chip yet either. Any with battery backup and i2c would be ok..

I need to remove two pads from the footprint so I can route a wire there.... :-)

If the minutes is green and on the 3'rd led (15 minutes past) and the seconds is red I want the 2'nd led to be fully red and then the 3'rd led will become more and more yellow (mix red/green) and the 2'nd led to be dimmer and dimmer during the 5 seconds it takes for the seconds to go to the 3'rd led.

So it will be a smooth transition between the leds - at least for the seconds. Maybe also for the minutes...

The routing is almost as retro as the visual design of the clock. I've mostly routed it with the free-angle tool so it almost looks like I've done it with tape as we did back in the 70'ies before computer pcb cad.

sqkybeaver wrote:for the coin cell i suggest changing the center pad to a circle the size of the cell, the solder mask around the pad can prevent contact with the pad.

Done. I usually put a small blob of solder in the pad to raise it up a bit, but here there's no other tracks passing under the battery holder so the increased pad size -method works fine here.

Bertho wrote:Does the PCB manufacturer accept inner angles this sharp or do you need to make remarks on the outline to get it made right?

I've no idea... I hope that they will mill as close as possible to the outline in accordance to their bit size, and that they leave "unreachable" board rather than taking away extra to reach the edge. I'm sure they will complain if it will destroy the pcb. I fear that asking them (Seeedstudio) how it should be done and what they can handle would just result in some random incomprehensible google-translated reply. So I'll just try and see what happens. :-)

AndThen wrote:If not I propose one small change. To the led drive traces nudge them apart and add "solder jumper" to each. So the arms can be sawn off and extended with wires.

That's a fun idea. Why not.... Were would the best cutoff point be you think?